In vitro activity of ceftazidime-avibactam, ceftolozane-tazobactam, and other comparable agents against clinically important Gram-negative bacilli: results from the 2017 Surveillance of Multicenter Antimicrobial Resistance in Taiwan (SMART).

OBJECTIVES

We investigated the in vitro antimicrobial susceptibilities of clinically important Gram-negative bacteria (GNB) from 16 major teaching hospitals in Taiwan in 2017.

MATERIALS AND METHODS

(n=686) and bloodstream isolates (n=673), non-typhoid (NTS; n=221) from various sources, species (n=21) from fecal samples, and (n=129) from the genitourinary tract were collected. Antibiotic minimum inhibitory concentrations (MICs) were determined using the broth microdilution method. Alleles encoding carbapenemases (KPCs), New Delhi metallo-β-lactamases (NDMs), Verona integron-encoded metallo-β-lactamase, imipenemase, , and -1-5 genes were detected by molecular methods in Enterobacteriaceae isolates.

RESULTS

Five (0.7%) isolates harbored -1 alleles. Twenty-four (3.6%), seven (1.0%), four (0.6%), and one (0.15%) isolates contained , , -1, and , respectively. Three (1.4%) NTS and no isolates harbored -1 genes. Seventy-one (10.5%) isolates displayed non-susceptibility (NS) to carbapenem agent(s). Phenotypically extended-spectrum β-lactamase (ESBL)-producing isolates showed significantly higher rates of ertapenem, tigecycline, and ceftolozane-tazobactam (CLZ- TAZ) NS (40.2%, 16.3%, and 71%-80%, respectively) than isolates exhibiting ESBL phenotypes (5.4%, 0.7%, and 18%-28%, respectively). All phenotypically ESBL-producing isolates were ceftazidime-avibactam (CAZ-AVB) susceptible. Two (8.3%) KPC-producing isolates showed CAZ-AVB NS. Hospital-acquired isolates were significantly less susceptible to ertapenem and CLZ-TAZ than hospital-acquired isolates.

CONCLUSION

Third-generation cephalosporins remain the optimal choice for treating NTS, , and gonococcal infections in Taiwan. Hospital-acquired and phenotypically ESBL-producing are a heavy resistance burden in Taiwan.